1. Technical Field
The present disclosure relates generally to document browsing on a portable electronic device, and more specifically to techniques for panning and zooming in a large document, such as a computer aided design (CAD) drawing, in response to orientation of the portable electronic device.
2. Background Information
It is increasingly common for users to access and browse documents on portable electronic devices, such as ultra mobile personal computers (PCs) (collectively UMPCs), tablet PCs, personal digital assistant (PDAs), electronic book (e-book) readers, cellular telephones, digital cameras, and the like, rather than use paper copies (e.g., “hard copies”) of the documents. The use of portable electronic devices has relieved users of the burden of maintaining and transporting large volumes of paper while in the field. However, limitations of many portable electronic devices have hindered the document browsing experience. These limitations are particularly acute when a user attempts to browse or otherwise interact with a “large” document, i.e., a document whose dimensions and/or level of detail is such that it cannot be displayed at a discernable size all at once on a display screen of a portable electronic device.
Browsing large documents on a portable electronic device using conventional techniques is typically a frustrating endeavor. Navigation about a large document is often difficult, since portable electronic devices typically have small navigation controls (e.g., small buttons). A user may have difficulty selecting a desired navigation control, due to its size and proximity to other controls. Similarly, a user may have difficulty manipulating the navigation control in a precise manner once selected, due to its small size.
This difficulty is often compounded by the small size of the display screen found on most portable electronic devices. With a small display screen, a user typically can only view a small portion of a large document at any one time (with features displayed at a discernable size). The smaller the display screen, the more a user must pan about a large document, to view different portions of it. Further, the smaller the display screen, the more a user must zoom in and zoom out of the document, to select areas of the document to view in more detail, and then return to a global view. Consequently, the small display screen included in many portable electronic devices increases the frequency a user must manipulate the small navigation controls, compounding the frustration.
While these issues occur in many different types of applications involving browsing large documents on portable electronic devices, one application in which these issues are particularly acute is the browsing of CAD drawings. CAD drawings typically have large dimensions and include significant low-level detail. As such, a builder, engineer, architect or other user attempting to browse a CAD drawing on a portable electronic device typically must pan and zoom repeatedly, to see the low-level detail of the drawing, and to understand the overall design. Yet, as discussed above, such panning and zooming may turn out to be a frustrating ordeal using conventional navigation controls.
Several strategies have been proposed to attempt to alleviate some of the issues of browsing large documents on portable electronic devices. However, such previously proposed strategies have notable shortcomings. For example, it has been proposed to provide larger displays on portable electronic devices. However, this may add unwanted size to the devices, decreasing their portability, while also significantly increasing their manufacturing cost. Similarly, various schemes have been proposed for providing enhanced pointing devices, for example, integrating larger, more responsive touch pads or touch screens into the devices. Yet again, this may impact the portability of the devices and significantly increase manufacturing cost.
Some have proposed avoiding the use of a pointing device altogether, and, instead, detecting movement applied to the portable electronic device itself. This detected movement would then be used to control navigation within a document. However, these schemes also have had significant shortcomings. Such schemes typically have relied on an accelerometer to detect movement applied to the portable electronic device. The inclusion of an accelerometer may add unwanted expense and complexity to the device. Further, an accelerometer has intrinsic limitations in the type of information it can provide and the calibration it requires. For example, an accelerometer typically will suffer from “drift” over time, and requires periodic reset by a user to return acceptably accurate results.
Further, previously proposed schemes that looked to movement applied to a portable electronic device, have generally required extreme and/or uncomfortable movements to perform certain types of navigation. For example, a user may be required to move the device through a large angle (e.g., an angle greater than 720°) without pause, to perform certain types of navigation. Similarly, a user may be required to perform complex simultaneous movements and tilts, challenging their manual dexterity. Accordingly, a user may find browsing a document using one of these previously proposed schemes to be difficult, non-intuitive and generally frustrating.
Accordingly, there is a need for improved techniques for browsing large documents on a portable electronic device, and in particular for panning and zooming within a large document being displayed on a portable electronic device.